A tone setting in a conventional electronic musical instrument for adapting the latter to a specific instrument such as a piano or organ has been performed by either of two schemes shown in FIGS. 5 and 6, respectively. According to the first scheme shown in FIG. 5 which illustrates a portion of an electronic piano panel including a plurality of tone setting switches 1-1 to 1-8 and a corresponding, number of light emitting diodes 2-1 to 2-8, one of the setting switches which corresponds to a desired instrument, is turned on. When a tone of piano 1 is to be obtained, the switch 1-1 is turned on upon which the corresponding light emitting diode 2-1 is activated. Alternatively, when it is desired to obtain the tone of a harpsichord, the switch 1-6 is turned on. An output signal corresponding to a switch thus turned on is supplied to a tone generator (not shown) to produce a desired tone signal.
In the second scheme shown in FIG. 6, each of the tone setting switches 1-9 to 1-13 corresponding to different types of instrument is associated with a plurality of light emitting diodes 2-9 to 2-12 corresponding to individual instruments belonging to each instrument type. When the switch 1-9 is turned on once, the light emitting diode 2-9 is activated and a string instrument is set. In this case, a pulse is generated which is counted by a pulse counter which is reset every five counts and whose output is supplied to a tone generator. By depressing the switch 1-9 again, the light emitting diode 2-9 is extinguished and instead thereof light emitting diode 2-10 is lit, showing a setting of a flute tone, and the pulse counter supplies its output of two counts to the tone generator. Thereafter, when the switch 1-13 is depressed to turn it on, the light emitting diode 2-9 is lit, indicating a guiter set. In this case, an output is sent to the counter corresponding to the switch 1-9 to reset the latter and to a counter corresponding thereto to count one which is sent to the tone generator. That is, in FIG. 6, any of the switches 1-9 to 1-10 is depressed repeatingly until a desired tone in tones belonging to the depressed switch is set.
In either of the cases shown in FIGS. 5 and 6, the operation of any switch or the number of operations of any switch, energization and deenergization of light emitting diodes and signal output to the tone generator can be processed by a micro processor.
The tone setting in such a conventional electronic musical instrument in which a plurality of switches together with light emitting diodes are arranged in a plane is satisfactory when the number of tones is limited. However, with the recent tendency of an increased number, say, one hundred, different tones, it becomes difficult to arrange a number of switches and associated light emitting diodes in a plane. For example, in the system shown in FIG. 5, in order to arrange 100 switches, a panel area therefor becomes very large providing no space for associated light emitting diodes. In order to realize 100 tones in the example shown in FIG. 6, it may be considered to provide 12 switches to each of which 8 light emitting diodes are allocated. In such a case, however, any one of the switches must be depressed 8 times when an immediately preceding tone is to be selected. This is not practical. Further, when the number of switches is to be reduced for some reason, the number of light emitting diodes for each switch must be increased, resulting in a further increase of depressing times of each switch.